The introvert: Sara Maitland

This is a very odd book. Or perhaps it is a normal book about a culture that feels very odd to me. In the world that Quiet describes, more than 30 people who dislike "mandatory group activities" fly across a continent and spend a weekend in a group for those who define themselves as "highly sensitive". They all know their Myers-Briggs personality types and are happy to write them up on a flip chart. They share bedrooms with strangers; listen to lectures and have deep and meaningful conversations at a series of collective meals. It sounds like hell to me.

Cain's argument is clear and interesting, though not original: over the past century the US has moved from a "culture of character" to a "culture of personality", as social admiration has shifted from ideals of private honour to public perception. This has led to the inexorable rise of the "extrovert ideal" and the "new groupthink" – the belief that a team or collective is more intelligent and creative than the individuals who form it. Cain believes, firstly, that this is not actually the case, and, secondly, that it not only wastes the talents but also pathologises the psyches of the 30% or so of the population (including herself) who are introverts.

I think this is silly. Perhaps it is true in the US, but it is not true in Britain. We have not idealised extroversion. Most people in Britain would still rather be described as sensitive, spiritual, reflective, having rich inner lives and being good listeners than the opposite. (And, incidentally, I am not at all persuaded that introverts are "good listeners" – in my experience we usually can't be bothered.) I think we in Britain still admire the life of the intellectual over that of the salesman; of the composer over the performer (which is why pop stars constantly stress that they write their own songs); of the craftsman over the politician. I cannot imagine even a rabid evangelical minister saying – as he does in Cain's book – that he is certain that "Jesus was an extrovert".

More profoundly, I think Cain is setting up a new binary which does not hold water. Extrovert and introvert are simply not the same sort of things as female/male, black/white or alive/dead. I think it is more useful to see the terms as adjectives, describing points on a long, loose arc than as identities. I joyfully live one of the most "introverted" (and, indeed, quiet) lifestyles of anyone I know, but I do not tick all the boxes on any of the tests for introversion I have tried out this past week. And in fact, despite all the statistics, research surveys and genetic and neuro-physiological data that Cain throws at it (and those are here in abundance), she admits that there is no agreement on the definitions, the dividing line or the meanings of the two terms.

What is truly odd about this book, however, is that it completely ignores real and actual "extreme introverts", because Cain speaks to no solitaries. Apart from one sentence about the great quiet happiness of some unidentified Buddhist monks (tell that to the rebels of Burma), the question of "contemplative" lifestyles is ignored. Perhaps more interestingly, she also declines to speak to self-employed sole traders, artists and craftspeople. My neighbour has just gone past on his quad bike, heading up the hill to his sheep – he works alone every day and has almost certainly never been in an open-plan office. I bet he does not see himself as an oppressed introvert, but as someone very lucky, whose independence and dignity are a fair price to pay for a smaller wage.

If people want quiet, there are lots of opportunities – they do not have to be "introvert" CEOs of American companies. Why would they want to? And at the very least, they don't have to fly to weekend conferences to celebrate their sensitivity, introversion and quietude.

In fact, this is a remarkably noisy "extroverted" book, bombarding the reader with a massive range of unharmonious "facts" and psychobabble ("over stimulating", to use one of Cain's terms). Even the language is an assault; you have to work through too many sentences like: "HBS grads likely have influenced your life in ways you're not aware of" and a barrage of split infinitives, acronyms and potted fashion summaries of what individuals are wearing.

Lovers of quiet won't like Quiet – we would rather go for a nice walk in the country.

The extrovert: Miranda Sawyer

This book has a simple, convincing idea at its heart: that the western world, particularly the US, has become so enamoured of what Susan Cain calls the "extrovert ideal" that it is missing out on the talents of half its population. If you can't speak in public, wilt in meetings and hate networking, then you are an introvert and you are destined to be ignored by an attention-deficit world.

Cain argues – correctly, I think – that this is mad. Why would you want to force someone into a salesman's role when what they're good at is hunkering in front of a computer, working through data? But loners are now seen as failures: kids who hang about by themselves are urged to join in, offices are designed without walls, you're judged by how many friends you have on Facebook. It's a strong point and Cain brings in serious data to back it up. People working in groups will more often come up with the wrong answer to a question, whereas when they approach the same problem separately, they get things right.

Cain gives an interesting precis of how our view of one another has changed since the early 1900s. Before then, it was someone's character that was held high: was he honourable, did she have integrity? But during the 20th century, the idea of personality took hold, so that the ideal citizen became charismatic, social, fascinating. All extrovert traits. There's another revealing section where she visits Harvard Business School to discover that everyone there is being trained to speak with conviction in groups, to say something, anything, even if they're not sure what they're saying is right. Just like a politician.

After a while, though, I found her thesis grating. Not every introvert is an unrecognised genius. Not every extrovert is an idiot thug. And we don't all fall neatly into one category. As the "extrovert" reviewer, I'd like to say I found reading Quiet hard to fit in among the cocktail parties, grime all-nighters and table-thumping meetings that make up my life. But that wouldn't be true, because, like most journalists – most humans – I'm a mixture of extrovert and introvert. I enjoy a party. But I also love spending time on my own writing and reading. So am I an introvert who has learned extrovert strategies? Or the other way about?

The problem with Cain's thesis is that she's so keen to convince us of its all-encompassing brilliance that she bends it out of shape. When she talks to an inspiring college professor, who gives wonderful speeches and spends lots of time with his students, she deems him an introvert because, afterwards, he likes to go home and sit quietly with his wife. That's not introverted. That's tired. When she cites a tale of an (individualistic, extrovert) American student who asked his (group-minded, introvert) Asian housemates if they wouldn't mind doing the washing-up sometimes, she says that the Asians were shocked because, for them, "it wouldn't be worth upsetting the group over a few dirty dishes". Surely if they were that quietly group-minded, they would have done the dishes in the first place?

And there is little acknowledgement from her that we change according to our life stages. As you age, you learn that shyness is a waste of time. Nobody is looking at you, judging you by your shoes. So why not stop worrying and start engaging with the world?

In the end, Cain's insistence that one of two sizes fits all means that this book becomes little more than another Men Are From Mars, Women Are From Venus tick-box work. People are more complicated, mutable, subtle and surprising than these either-or categories. Yes, attention-seekers are a bore, but so are tongue-tied nerds. For me, it is our civic duty to be neither, to know when to pipe down and when to speak up. And most of us – the ones who aren't pop stars, or inventors – manage to do that quite well. Apparently, we're ambiverts. I'd just call us polite.